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C. J. HOHENSTEIN.

sown RECORDING APPARATUS.

N0. 356 877. Z2971 Patented Feb, 1, 1887.

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WITNESSES: E9711 l/IIVE/Vfbfi- A TTUR/VEXS.

lUnirnn drains CARL J. HOHENSTEIN,

Parlour @FFllCEQ OF NEW YORK, N. Y.

SOUND RECORDING APPARATUS.

SPEC'EFICATION forming part of Letters Patent No. 356,877, datedFebruary 1, 1887.

Application filed August 10, 1886. Serial No. "210,524. {No model.)

To all 2071/0722, it may concern:

Be it known that I, CARL J. Honnnsrnrn, a citizen of the United States,residing at New York, in the county and State of New York, have inventedcertain new and useful Improvements in $ound Recording Apparatus, ofwhich the following is a specification, reference being had to thedrawings accompanying and forming a part of the same.

The object of my invention is to produce an instrument by means of whichsounds of any kind, whether simple musical tones or articulate speech,maybe permanently recorded and reproduced at will. The special object ofthe construction which I have devised is to obtain a more sensitiveapparatus of the hind than has heretofore been made.

In carrying out my invention I make use of a reflector which issupported in such manner that it is capable of a slight movement oroscillation about an axis. Upon this reflector a beam of light isdirected, and it is reflected upon a stationary reflecting mirror placedat a certain distance in front of the vibrating reflector. lhereflectingmirror is slightly concave and concentrates the reflected raysof light to a focus. To obtain a movement or vibration of the focusedrays corresponding to sound-waves, I either connect with the firstnamedreflector a vibrating diaphragm or use the reflector itself as adiaphragm, so that speaking against it will impart to it a certainmovement or vibration. These vibrations are imparted to the beam oflight and are greatly amplified in the focused rays, so that if a stripof sensitive photographic paper be drawn through the focused rays thechange of position of the latter will be recorded by an undulating lineupon the paper. The strip may then be developed in the usual manner andthe line reproduced in various ways, as by engraving or photo engravingor otherwise. *When obtained in a permanent form in metal, the strip maybe drawn underastylus orother point connected with a diaphragm and thesounds or words reproduced any number of times.

The main advantage of this instrument over ordinary forms of phonographor similar instruments residcsin the fact that it may easily be madeextremely sensitive. The vibrating reflector may be used with thediaphragm of an ordinary telephonereceiver in circuit with a microphone.and the slightest vibrations so greatly amplified as to reproduce soundsor words uttered a long distance from the micro phone.

Many other uses will be suggested by the accompanying description of thenature of the invention, in which reference is made to the drawings.

Figure 1 is a side elevation of the parts comprising the recorder, theside of the box being removed. Fig. 2 is a top plan view of the sameparts, the top of the box being removed. Fig. 8 is al'ront view of thevibrating reflector and its supports. Fig. a is a side view of the samewithout the supports. Fig. 5 is a modifled support for the reflectorwhen the latter is used without a diaphragm. Fig. 6 is a plan view ofthe device for moving a strip of photosensitive paper through thefocused light rays. Figs. 7, 8, and 9 are different forms of tracer orstylus used in reproducing sound. Fig. 10 is a supporting-plate used inthe device shown in Fig. 6. Fig. 11 is a portion of a screw-threadedshaft used in the same. Fig. 12 is a modification of Fig. 6, shown inside elevation. Fig. 13 is a top view, and Fig. 14 a rear View, of thesame. Fig. 15 is a side view of the device for reproducing the sound.Fig. 16 is a top view of the same with the diaphragm and its supportsremoved. Fig. 17 is a side view illustrating the manner of using a platemade by the instrument in Fig. 12 in reproducing speech. Fig. 18 is atop view of the same.

The recording apparatus is contained in a close box, A. it consists ofthe following parts: A small circular reflector, B, is soldered orotherwise secured to a metal pin, B, which serves as a supporting-axis,being mounted between suitable supports, (6 c. A metal or otherdiaphragm, O, is mounted in a suitable mouth-piece, O, and the reflectoris supported a short distance from it. A resilient connection is madebetween the diaphragm and the reflector, as by a rubber band, 0, whichis passed through holes in the two. A short pin, a, is then interposedbetween the central point of the diaphragm and a point on one side ofthe axis of the reflector, so that any vibration tion or angulardisplacement about the axial supporting-pin B, and this is true, and inlarge measureimmaterial with reference to ultimate results, whether theline with reference to which the reflector turns pass through thereflector or be situated at a greater or less distance from it.

In the interior of the box A, but out of line with the reflector B, isplaced a box. or darklantern, D, adapted to containa lamp, candle,electric lamp, or other suitable source oflight. In the side of thelantern is an adjustable or telescopic tube, D, which directs the lightupon the reflector B. I have a special object in using an adjustable ortelescopic tube for this purpose, for the reason that it may be made toincrease or diminish the area of the light-surface upon the reflector,and thus provide a means of adjusting the instrument, as willhereinafter more fully appear.

The light-rays reflected from the reflector B fall upon a concavereflector, E, placed at the opposite end of the box. The beam of lightdoes not entirely cover this reflector, butleaves an annular spacearound the edge. By the reflector E the rays are concentrated andfocused at a point near the front of the box,

and in the focus is a strip of photo-sensitive paper, (1. Any suitableprovision is made for holding, moving, and receiving this strip. Forexample, I employ a spool, (1, upon which it is wound. It is thencarried over a roll, 6, and passed between the same and a roll, 6,provided with a crank. The rolls 0 and e being close together, the stripis unwound by friction and delivered in a receptacle, f.

In order to produce a record, the light is adjusted as above described,the voice directed into the mouth-piece,and the handlef turned. Thevibration of the diaphragm imparts oscil .lations to the reflector B,and this produces corresponding vibrations or displacements of the beamof reflected light. These displace ments are amplified by the reflectorE, owing to its position and distance from the reflector B, and thefocus of the reflected rays is shifted by each displacement of thelight-surface on reflector E. If while the light-rays are being thuseffected the sensitive strip is moved at an even rate, a photographicimpression of the focus in all its positions will be taken, forming awavy or undulating line. The paper is afterward developed and theimpression fixed in the ordinary manner.

The construction or the arrangement of the reflector B and diaphragm maybe somewhat varied. For example, in lieu of using a diaphragm connectedwith the reflector, the diaphragm may be dispensed with and thereflector made large enough to serve as a diaphragm itself. In this caseit is advisable to pass a rubber cord, 1), around the projection or car,as indicated in Fig. 5, in order to hold the reflector better in itsposition. On the other hand, in lieu of using a strip of photosensitivepaper, I may use a cylinder upon ascrew-shaft, F, such as is shown inFig. 6, and cover the surface with a sheet of sensitive paper. Thescrew-shaft is caused to enter a threaded bearing, so that the cylinderwhen turned has an endwise movement,which takes the impression in aspiral line. \Vhen the cylinder 0 is used merely to move a paper strip,its surfaceis covered with rubber to prevent slipping. It is thenmounted with one end of the axle in a hole in a supportingplate, F,which is secured in position by screws that pass through the slots f Theend of the screw-threaded axle is provided with a suitable bearing, asg, which will turn freely in the plate F.

Another way of taking an impression ofthe path of movement of the focusis to employ a sensitive glass plate. The light is focused upon thesurface of this plate and a movement is imparted to the plate thatcarries it under the focus in aspiral path. An instrument for thispurpose is shown in Figs. 12 to 14. G is the sensitive plate secured ina holder, 9, by clamps 57 The holder is mounted in a hearing that isadapted to slide to and from a supporting-guide, H, The back of theholder carries a raised spiral, H, that engages with a set of teeth, h,on the support. On turning the handle h the plate is revolved, and atthe same time moved horizontally by the spiral H engaging successivelywith the teeth 72-.

Having obtained a photographic record of the sound waves or impulses inany of the ways abovedescribed, the next step is to engrave or photoengrave the impression in metal or some other hard substance, to make apermanent recordthat can be used for repr0- ducing the sounds. In someinstances I use a strip of metal and cut it along one edge to correspondto the line traced by the focus. This irregular line, as abovedescribed, is obtained when the vibration of the beam of light shiftsthe position of the illuminated surface ICO illuminated surface is lessin area than the refleclor and is vibrated from side to side, the

focus will change. On the other hand, if the illuminated surface justequal in area that of the rcflector,'t-hen by the vibration ofthe beammore or less light will pass beyond the reflector, and the luminosity ofthe focus will vary, making a line upon the sensitive paper of dark and.light portions. In reproducing this line by photo-engravinga line ofunequal depressions will be formed. There are other ways of effectingthe same result, which will be Well understood from the foregoing.

To reproduce sounds from the record made as described, I pass the recordunder a tracer or stylus attached to a diaphragm. The tracer is attachedto the diaphragm in the same manner as the reflector, and I may useeither with the same diaphragm by simply substituting one for the other.The tracer shown in Figs. 7 and 8 is a small piece of metal having apoint, 74, and a shoulder, k, and forming part ,the undulating track orgroove.

of a bell-crank lever provided with a hole, Z, for the spindle in Fig.9, by which it is supported when a vertical movement is to be impartedto the tracer. At Z is anotherhole, through which the spindle in ispassed when the tracer is to be used with a record that imparts to it anoscillating movement. In the first supposed case a needle, in, is placedbetween the tracer and the diaphragm, and a rubber cord is passedthrough the hole Z and one or more holes in the diaphragm. In the secondassumed case the cord is passed through the hole Z and the center of thediaphragm, and the position of the needle may remain as before.

If a strip of metal be cut so that its edge conforms to the photographedline of undulations, it is used with the tracer by drawing it through aslot, at, in a guide, a, with its out edge in contact with the shoulderis. The ine qualities in the edge of the strip produce verticalvibrations of the tracer and reproduce the original sounds.

If the record be engraved or photo-engraved on a metal strip, the latteris drawn past the tracer in such manner that the point It enters If therecord be one produced by variations in theluminosity of the focus, asabove described, the movement of the tracer will be vertical; but if therecord is a wavy line the point will be oscillated from side to side andthe vibrations produced in that way.

The record obtained on a plate may also be engraved or photoengraved ina metal plate and reproduced by placing a diaphragm provided with apointer in front of the plate, as in Figs. 17 and 18. The point Itshould extend into the engraved track, so that by turn ing the handleand revolving the plate it will follow the spiral course of the track.The mechanism in this case is the same, so far as the supportfor theplate is concerned, as that shown in Figs. 12, 13, and 14, and describedabove, and is therefore correspondingly lettered. The diaphragm andtracer are of the same construction as in the other devices.

This apparatus or means of recording and reproducing speech is capableof many and useful applications. It is more sensitive than any of whichI am aware, and by it a photographed record of ordinary sounds may beobtained in which the length of the vibrations or undulations of lightfocus is several inches.

This makes it useful in connection with telephones or microphones, forthe purpose of recording the words or sounds transmitted by them, andsuch use would be facilitated by making the reflector B of iron andplacing the receiving-magnet immediately behind it.

I have not described all t-he.various ways in which this instrument maybe constructed and used; but I do not limit myself to the precise formsshown.

I am aware that sound has been transmitted by means of a reflected beamof light, and I am also aware that a reflector has been used inconjunction with a diaphragm for producing changes in a reflected beamof light corresponding to the vibrations of the diaphragm, and these,therefore, are matters which I do not claim.

7 What I claim is- 1. In an apparatus for recording sound, thecombination, with a source of light and a movable photo-sensitivesurface, of a reflector for producing movements or vibrations of or in abeam of light, and mounted upon an axis or pivotal support, whereby thesound-waves produce therein an oscillating movement about said axis orsupport, as set forth.

2. In an apparatus for recording sound, the combination, with a sourceof light and a movable photosensitive surface. of a reflector forproducing movements or vibrations of or in a beam of light, and mountedupon an axis or pivotal support, and a diaphragm connected with saidreflector, whereby the vibrations in the diaphragm produce oscillationsin the reflector about its axis or pivotalsupport, as set forth.

3. In a sound-recording apparatus, the combination, with a system ofreflectors and a movable photo-sensitive surface,of an inclosed sourceof light and an adjustable or telescopic tube for directing a beam oflight upon the vibrating reflector, as herein set forth.

4. In a sound-recording apparatus, the combination, with asource oflight and a movable photo-sensitive surface, of a pivoted reflector, adiaphragm for imparting oscillations or vibrations thereto, a needle orrigid metal piece interposed between the diaphragm and reflector, andone or more elastic bands for bold ing the reflector in position withreference to the diaphragm.

CARL J. HOI-IENS'IEIN.

\Vitnesses:

Boer. F. GAYLORD, PARKER W. PAGE.

